Platinum source compositions for chemical vapor deposition of platinum

ABSTRACT

A platinum source reagent liquid solution, comprising: 
     (i) at least one platinum source compound selected from the group consisting of compounds of the formulae: 
     (A) RCpPt(IV)R&#39; 3  compounds, of the formula: ##STR1## wherein: R is selected from the group consisting of hydrogen, methyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl, t-butyl, trimethylsilyl and trimethylsilyl methyl; and each R&#39; is independently selected from the group consisting of methyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl, t-butyl, trimethylsilyl and trimethylsilyl methyl; and 
     (B) Pt(β-diketonates) 2  of the formula: ##STR2## wherein: each R&#34; is independently selected from the group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, trifluoromethyl, perfluoroethyl, and perfluoro-n-propyl, and 
     (ii) a solvent medium therefor. 
     The platinum source reagent liquid solutions of the invention are readily employed in a chemical vapor deposition process system including a liquid delivery apparatus for volatilizing the source reagent liquid solution and transporting the resulting vapor to the chemical vapor deposition reactor for deposition of platinum on a substrate mounted in the CVD reactor.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 of U.S.Provisional patent application No. 60/000764 filed Jun. 30, 1995 in thenames of Thomas H. Baum, Peter S. Kirlin, and Sofia Pombrik for"Platinum Source Compositions for Chemical Vapor Deposition ofPlatinum."

This is a division of U.S. application No. 08/673,372.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the formation by chemical vapor deposition ofplatinum and platinum-containing films, using source reagent solutioncompositions of platinum-containing source compounds and complexes.

2. Description of the Related Art

Ferroelectric thin films formed of oxide compositions such as strontiumbismuth tantalate (SrBi₂ Ta_(x) O_(y)) are potentially useful ascapacitor materials for the fabrication of microelectronic devices suchas dynamic random access memory (DRAM) devices.

Various means and methods for deposition formation of such ferroelectricfilms have come into use or otherwise been proposed in the art,including sol-gel, spray pyrolysis, aerosol and liquid delivery chemicalvapor deposition (CVD) techniques. The CVD approach is particularlyadvantageous because it enables high aspect ratio features to beefficiently coated and conformal films to be deposited over non-planarsurface topographies.

In the fabrication of DRAM (as well as FRAM) devices, platinum metal(Pt) often is utilized as an electrode for the device. It would bedesirable to form the platinum films by CVD as well, to integrate themanufacturing steps efficiently.

The chemical vapor deposition of Pt films over small-scale, localizedareas has been carried out successfully using various solid precursors,including for example tetrakis (trifluorophosphine) platinum, bis(β-diketonate) platinum, (cyclopentadienyl) platinum trimethyl, and(alkylcyclopentadienyl) platinum trimethyl, and inducing deposition ofthe platinum over the localized area by focused ion beam, electron beam,or laser decomposition of the platinum precursor. This technique may beused for, e.g., formation of platinum interconnects, microsurgery tocorrect subsurface chip defects, or repair of x-ray masks, as describedin Tao and Melngailis, U.S. Pat. No. 5,104,684, "Ion Beam InducedDeposition of Metals." In general, such precursor compounds havesuperior volatility characteristics, being readily volatilized bysublimation from the solid phase in conventional bubbler-based transportsystems for subsequent chemical vapor deposition in the depositionreactor. In consequence, the use of such conventional bubbler-basedtransport systems for forming the vapor of these solid precursors forplatinum has proven sufficiently advantageous in terms of the rate oftransport of the platinum source vapor to the downstream CVD reactor, sothat alternative delivery techniques have not been actively sought.

However, when it is desired to form larger area platinum films withcontinuous coverage of surfaces of various geometries, there aresuggestions that mass transport of these platinum reagents to thedeposition reactor may be inadequate. For example, as reported in"Chemical Vapor Deposition of Platinum, Palladium and Nickel," Alfred A.Zinn, et al., in The Chemistry of Metal CVD, edited by Toivo T. Kodasand Mark J. Hampden-Smith, VCH Verlagsgesellschaft mbH, Weinheim,Germany and VCH Publishers Inc., New York, p. 337, low growth rates ofplatinum were reported and attributed to "an inadequate supply of theprecursor to the reactor."

Examples of prior art CVD-based platinum deposition process technologyinclude the compositions and coating formation technology disclosed inU.S. Pat. No. 5,130,172 issued Jul. 14, 1992 to Robert F. Hicks, et al.and U.S. Pat. No. 5,403,620 issued Apr. 4, 1995 to Herbert D. Kraesz, etal., which teach to form a platinum coating on a substrate fromorganometallic compounds such as (trimethyl)(cyclopentadienyl)platinumin the presence of a reducing fluid such as hydrogen gas.

In general, the transport rate of source reagent vapor to the CVDreactor in CVD process systems has a substantial impact on the ease andeconomics of operating such systems, and a means and method whichmarkedly increases such transport rate of the reagent source material tothe CVD reactor represents a significant advance in the art of chemicalvapor deposition.

It therefore is an object of the present invention to provide animproved composition, means, and method for delivery of platinum sourcematerial to the reactor of a chemical vapor deposition process system.

It is another object of the invention to provide an improved Pt CVDprocess, which provides faster film growth rates via liquid delivery andeliminates the deleterious effects of having hydrogen in contact withcapacitor "oxides" at elevated temperatures (i.e., ≧500° C.), when Ptelectrodes or other Pt thin film structures are formed on oxidesubstrates, as hereinafter more fully disclosed.

Other objects, features and advantages of the present invention will bemore fully apparent from the ensuing disclosure and appended claims.

SUMMARY OF THE INVENTION

The present invention broadly relates in a compositional aspect to aplatinum source reagent liquid solution, comprising:

(i) at least one platinum source compound selected from the groupconsisting of compounds of the formulae:

(A) RCpPt(IV)R'₃ compounds, of the formula: ##STR3## wherein:

R is selected from the group consisting of hydrogen, methyl, ethyl,i-propyl, n-propyl, n-butyl, i-butyl, t-butyl, trimethylsilyl andtrimethylsilyl methyl; and each R' is independently selected from thegroup consisting of methyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl,t-butyl, trimethylsilyl and trimethylsilyl methyl; and

(B) Pt(β-diketonates)₂ of the formula: ##STR4## wherein: each R" isindependently selected from the group consisting of methyl, ethyl,n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, trifluoromethyl,perfluoroethyl, and perfluoro-n-propyl, and

(ii) a solvent medium therefor.

The solvent medium in such solution may for example comprise one or moresolvent species selected from the group consisting of hydrocarbons,ethers, alcohols and esters.

In a method aspect, the present invention relates to a process forforming a platinum coating on a substrate in a chemical vapor depositionreactor, comprising the steps of:

(a) providing a platinum source reagent liquid solution, comprising:

(i) at least one platinum source compound selected from the groupconsisting of compounds of the formulae:

(A) RCpPt(IV)R'₃ compounds, of the formula: ##STR5## wherein: R isselected from the group consisting of hydrogen, methyl, ethyl, i-propyl,n-propyl, n-butyl, i-butyl, t-butyl, trimethylsilyl and trimethylsilylmethyl; and each R' is independently selected from the group consistingof methyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl, t-butyl,trimethylsilyl and trimethylsilyl methyl; and

(B) Pt(β₃ -diketonates)₂ of the formula: ##STR6## wherein: each R" isindependently selected from the group consisting of methyl, ethyl,n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, trifluoromethyl,perfluoroethyl, and perfluoro-n-propyl, and

(ii) a solvent medium therefor;

(b) volatilizing the platinum source reagent liquid solution to form aplatinum source reagent vapor therefrom;

(c) transporting the platinum source reagent vapor to a chemical vapordeposition reactor; and

(d) depositing platinum from the platinum source reagent vapor on thesubstrate in the chemical vapor deposition reactor, under chemical vapordeposition conditions effective therefor.

Such chemical vapor deposition conditions may advantageously comprisethe presence of an oxidizing gas, e.g., oxygen (O₂), ozone (O₃), nitrousoxide (N₂ O) or mixtures thereof, particularly when the substratecomprises a perovskite oxide. Alternatively, the chemical vapordeposition conditions may advantageously comprise the presence of areducing gas, e.g., H₂ or NH₃, when such reducing gas is beneficial tothe Pt deposition process, or otherwise does not preclude the efficacyof the process or the deposited Pt film for their intended purpose.

In a preferred aspect, the volatilization and transport of the platinumsource reagent may be effected by a liquid delivery system of the typeas variously disclosed in U.S. Pat. No. 5,204,314 and pending U.S.patent application No. 08/280,143 filed Jul. 25, 1994 and issued Jul.16, 1996 as U.S. Pat. No. 5,536,323, and pending U.S. patent applicationNo. 08/484,025 filed Jun. 7, 1995 in the names of Peter S. Kirlin, RobinL. Binder, Robin A. Gardiner, Peter Van Buskirk, Jiming Zhang, andGregory Stauf, for "Source Reagent Liquid Delivery Apparatus, andChemical Vapor Deposition System Comprising Same," the disclosures ofwhich hereby are incorporated herein by reference in their entirety.

Other aspects, features and embodiments of the invention will be morefully apparent from the ensuing disclosure and appended claims.

DETAILED DESCRIPTION OF THE INVENTION, AND PREFERRED EMBODIMENTS THEREOF

FIG. 1 is a cross-sectional elevational view of a random access memory(RAM) device comprising a ferroelectric thin film capacitor structurewith platinum electrodes formed by chemical vapor deposition ofplatinum, according to one embodiment of the invention.

The present invention is based on the surprising and unexpecteddiscovery that a liquid delivery approach to the transport of a platinumsource reagent to a CVD reactor, using a source reagent liquid solutionwhich is volatilized to provide a vapor phase platinum source materialfor subsequent deposition from the vapor in the CVD reactor of platinum,can provide a high level of improvement, e.g., of 10-100 times relativeto the use of conventional bubbler-based reagent delivery to the CVDreactor, in faster film growth rates and higher manufacturing processthroughput of deposition substrates and output of CVD product articles.

In one preferred aspect, the liquid delivery method of the presentinvention is carried out in a manner at odds with the prevailingapproach in the art for effecting CVD of platinum. As discussed earlierin the "Background of the Invention" section hereof, Hicks et al. U.S.Pat. No. 5,130,172 and Kraesz, et al. U.S. Pat. No. 5,403,620 teach toform a platinum coating on a substrate from organometallic compoundssuch as (trimethyl)(cyclopentadienyl)platinum in the presence of areducing fluid such as hydrogen gas.

The Hicks et al. No. '172 and Kraesz, et al. No. '620 patents, togetherwith the published literature in the field of platinum film formationtechnology, provide a "conventional wisdom" consensus that reducinggases, such as hydrogen (H₂) and forming gases (H₂ in inert gases suchas helium, nitrogen and argon) are necessary for high-purity Pt filmgrowth. In fact, the applicants have determined that the presence andreactivity of hydrogen with complex perovskite oxides, e.g., in the CVDformation of conducting platinum electrodes on perovskite "oxide"capacitors, in accordance with the teachings of the Hicks et al. No.'172 and Kraesz, et al. No. '620 patents, can actually be detrimental tothe deposited capacitor or ferroelectric thin-film.

The present invention thus contemplates an improved Pt CVD process,which provides faster film growth rates via liquid delivery andeliminates the deleterious effects of having hydrogen in contact withcapacitor "oxides" at elevated temperatures (i.e., ≧500° C.), inrelation to the prior art Pt film formation processes. In instanceswhere the substrate and overall process are benefitted or at least notunduly adversely affected by the presence of a reducing gas in thechemical vapor deposition chamber, a reducing gas may be employed. Thus,the invention comtemplates that the vapor phase composition in thechemical vapor deposition step may potentially comprise other vapor orgas phase constituents, including reducing and oxidizing gas/vaporspecies, and/or any other species which are advantageously present inthe CVD step or at least do not preclude the efficacy of such step indeposition of Pt-containing film material.

It is a preferred aspect of the present invention, however, to utilizean oxidizing gas in the CVD step when depositing Pt on substratescontaining perovskite oxide components, or other substrate materialswhich are deleteriously affected by the presence of a reducing gas inthe CVD reactor.

In such aspect, the present invention improves on the current Pt CVDprocesses of the Hicks et al. and Kraesz et al. patents, and suchconventional wisdom prior art approach, by applicants' use of oxidizergas(es) such as oxygen (O₂), ozone (O₃), nitrous oxide (N₂ O), andmixtures thereof, in the Pt CVD process. The use of oxidizer gasesduring Pt CVD and electrode thin-film formation has several advantagesincluding, but not limited to:

1. oxidation of carbon-containing ligands and decomposition by-productsof the precursor and the solvent, providing high-purity, near-bulkresistivities.

2. oxidation of the Pt-perovskite interfacial region during nucleationand steady state film growth. This ensures that the surface of thecomplex oxide capacitor film is not deteriorated in an adverse manner inrespect of film stoichiometry, capacitance, dielectric constant,capacitance per area, and device performance.

3. Pt thin films readily allow oxygen diffusion throughout the metallayer at elevated temperatures and thereby ensure carbon removal in thefilm, at the interface, thereby obviating the concerns stated in thepreceding paragraph.

4. The use of oxygen/nitrous oxide provides a useful manufacturingscheme for thin film growth of Pt electrodes via a liquid deliverymethodology to perovskite based thin-film capacitors. Such process ishighly suitable for DRAM device production.

The platinum source reagent compounds which have been found to be wellsuited to liquid delivery CVD of platinum in the broad practice of theinvention include a wide variety of organoplatinum compounds andcomplexes, with platinum (II) bis (B-diketonates) and platinum (IV)(cyclopentadienyl) trialkyls being particularly preferred. In accordancewith the invention, these platinum source compounds-are dissolved atappropriate concentration in a suitable solvent medium, to form sourcereagent compound solutions Illustrative Pt source compounds of theinvention include:

(i) Pt (II) bis (1,1,1,5,5,5-hexafluoro-2,4-pentanedionato);

(ii) Pt (II) bis (2,2,6,6,-tetramethyl-3,5-heptanedionato)

(iii) Pt (IV) (methylcyclopentadienyl) trimethyl;

(iv) Pt(CO)₂ Cl₂ ;

(v) Pt(acac)₂ ;

(vi) Pt(PF₃)₄ ;

(vii) Pt(CH₃)₂ [(CH₃)NC];

(viii) (COD)Pt(CH₃)₂ ;

(ix) (COD)Pt(CH₃)(η¹ -C₅ H₅);

(x) (COD)Pt(CH₃)Cl;

(xi) (C₅ H₅)Pt(CH₃)(CO);

(xii) (C₅ H₅)Pt(allyl)

(xiii) (acac)Pt(CH₃)₃ ;

(xiv) (C₅ H₅)Pt(CH₃)₃ ;

(xv) (CH₃ C₅ H₄)Pt(CH₃)₃,

wherein: acac=acetylacetonate; C₅ H₅ =η⁵ -cyclopentadienyl; CH₃ C₅ H₄=η⁵ -methylcyclopentadienyl; COD=1,5-cyclooctadiene; and η¹ -C₅ H₅ =η¹-cyclopentadienyl.

Illustrative Pt compounds which are potentially usefully employed in thebroad practice of the invention include those described in Rand, M. J.,J. Electrochem. Soc. 1973, 120, 686; Kumar, R., et al., Polyhedron 1989,8, 551; Dryden, N. H., et al., Chem. Mater. 1991, 3, 677; Xue, Z., etal., Chem. Mater., 1992, 4, 162; Chen, Y. J., et al., Appl. Phys. Lett.1988, 53, 1591; and Xue, Z., et al., J. Am. Chem. Soc., 1989, 111, 8779.

The above-identified platinum source reagent compounds are exceedinglysoluble in hydrocarbons, ethers, alcohols and ester solvents, and can beutilized in high concentrations in the solutions of the invention.Illustrative solvent species which may potentially be usefully employedsingly or in mixtures in the practice of the invention include n-butylacetate, tetraglyme, isopropanol, tetrahydrofuran, hexane, heptane,octane, etc. Some illustrative specific solvent composition speciesinclude:

(i) a mixture of n-butyl acetate and tetraglyme,

(ii) a mixture of tetrahydrofuran and tetraglyme;

(iii) a mixture of n-butyl acetate and isopropanol;

(iv) a mixture of tetrahydrofuran, isopropanol, and tetraglyme; and

(v) n-octane.

The platinum source reagent compound solutions of the invention havedemonstrated utility for the deposition of high-purity platinum filmsand conductive layers. The physical and chemical properties of thesource reagent compositions and resulting films achieved in the broadpractice of the invention can be dramatically altered by small changesin the molecular structure of the source reagent compounds.

For example, the melting point of (MeCp) Pt Me₃ is 29°-30° C. while thenon-methylated analog (Cp) Pt Me₃ melts at 108° C. As a further example,substitution of the Me groups in (MeCp) Pt Me₃ with ethyl (Et) groupsyields corresponding liquid complexes. Similarly, fluoro substitution ofplatinum (II) bis (β-diketonates) leads to lower melting complexes withgreatly enhanced volatilities. The solubility of the these derivativesis higher than the analogous non-fluorinated platinum source reagentmaterials. It will therefore be apparent that the compositions of theinvention can be readily tailored to achieve high growth rates ofplatinum films by increased volatility and solubility of the platinumprecursors in organic media.

The platinum source reagent compounds usefully employed in liquid sourcereagent solutions according to the invention include source compounds ofthe formulae set out below:

(A) RCpPt(IV)R'₃ compounds, of the formula: ##STR7## wherein:

R is selected from the group consisting of hydrogen, methyl, ethyl,i-propyl, n-propyl, n-butyl, i-butyl, t-butyl, trimethylsilyl andtrimethylsilyl methyl; and each R' is independently selected from thegroup consisting of methyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl,t-butyl, trimethylsilyl and trimethylsilyl methyl; and

(B) Pt(β-diketonates)₂ of the formula: ##STR8## wherein: each R" isindependently selected from the group consisting of methyl, ethyl,n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, trifluoromethyl,perfluoroethyl, and perfluoro-n-propyl.

The above-described liquid solution compositions of the invention may beadvantageously employed for forming a platinum coating on a substrate ina chemical vapor deposition reactor, by volatilizing the platinum sourcereagent liquid solution to form a platinum source reagent vaportherefrom, and transporting the resulting platinum source reagent vaporto a chemical vapor deposition reactor. In the CVD reactor, the platinumis deposited from the platinum source reagent vapor on the substrate,under suitable chemical vapor deposition conditions, such as may readilybe determined without undue experimentation by those of ordinary skillin the art. Such chemical vapor deposition conditions may for examplecomprise the presence of an oxidizing gas, and (contrary to theteachings of the Hicks et al. No. '172 and Kraesz, et al. No. '620patents) the absence of hydrogen or other reducing gases. Alternatively,as discussed hereinabove, the chemical vapor deposition conditions mayinclude the presence of a reducing gas species, e.g., hydrogen, ammonia,etc.

The substrate may be of any suitable type and composition, and may forexample comprise insulating, dielectric, conducting, semiconducting,etc., materials, or combinations thereof. The substrate may for examplecomprise a semiconductor substrate with a device or other architectureor structure thereon, with respect to which the Pt material formed bythe method of the invention forms a component or operative part. Thesubstrate may for example comprise a perovskite oxide or othercomposition, and may comprise a diffusion barrier, wherein the diffusionbarrier includes a material selected from the group consisting oftitanium nitride, tantalum nitride, and titanium aluminum nitride.

The volatilization and transport of the platinum source reagent may beeffected by a liquid delivery system of any suitable type, as forexample a liquid delivery system and corresponding liquid deliverysystem operation as more filly disclosed in the aforementioned U.S. Pat.Nos 5,204,314, 5,536,323 issued Jul. 16, 1996, and pending U.S. patentapplication No. 08/484,025 filed Jun. 7, 1995 in the names of Peter S.Kirlin, Robin L. Binder, Robin A. Gardiner, Peter Van Buskirk, JimingZhang, and Gregory Stauf, for "Source Reagent Liquid Delivery Apparatus,and Chemical Vapor Deposition System Comprising Same," the disclosuresof all of which are incorporated herein by reference in their entirety.

The features and advantages of the invention are more fully illustratedby the following non-limiting examples, wherein all parts andpercentages are by weight, unless otherwise expressly stated.

EXAMPLE 1

A solution consisting of platinum (II) bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato) was dissolved in an organicsolvent (hydrocarbon, alcohol, ether, ester). The solution was deliveredto a warm-walled reactor using a liquid delivery system and thermallydecomposed in an O₂ /N₂ O mixture to deposit a Pt film. This film can beused as an electrode for DRAM applications or as a catalytic surface forsubsequent reaction.

EXAMPLE 2

A solution consisting of platinum (II) bis(2,2,6,6,-tetramethyl-3,5-heptanedionato) was dissolved in a solution ofn-butyl acetate and tetraglyme (25:1). This solution was delivered,using a commercial liquid delivery system, to a warm walled CVD reactorin an O₂ /N₂ O mixture to deposit thin, electrically conductive Ptfilms. These films can be used as circuits or electrodes for a varietyof microelectronic applications.

EXAMPLE 3

In a modification to Examples 1 and 2, a solution consisting of platinum(II) bis (2,2,6,6,-tetramethyl-3,5-heptanedionato) was dissolved in asolution of tetrahydrofuran and tetraglyme (25:1). This solution wasdelivered (using a commercial liquid delivery system) to a CVD reactorto produce high quality Pt films. The decomposition was performed in thepresence of O₃ or O₂ /N₂ O mixture to facilitate clean decomposition ofthe Pt source.

EXAMPLE 4

In a modification to Examples 3, platinum (II) bis(2,2,6,6,-tetramethyl-3,5-heptanedionato) was dissolved in a solution ofn-butyl acetate and isopropanol. The presence of the alcohol co-reactantfacilitates the decomposition and liberation of protonated2,2,6,6,-tetramethyl-3,5-heptanedione. The need for O₃ or O₂ /N₂ Omixture provide carbon-free films and ensures the capacitor thin-filmproperties for manufacturing.

EXAMPLE 5

A solution consisting of platinum (IV) (methylcyclopentadienyl)trimethyl was dissolved in an organic solvent (hydrocarbon, ether,ester). The solution was delivered to a warm-walled reactor using acommercial liquid delivery system and thermally decomposed to deposit aPt film. This approach enables faster film growth rates to be realizedby increasing the mass-transport of reactant to the heated substratesurface and therefore, is of greater utility than using conventionalbubbler systems. The deposited Pt film can be used as an electrode forDRAM applications, as an electrical conductor or as a catalytic surfacefor subsequent reaction (i.e. hydrosilylation, polymerization orhydrogenation).

EXAMPLE 6

In a modification of example 5, a solution of platinum (IV)(methylcyclopentadienyl) trimethyl was dissolved in a hydrocarbonsolvent, such as n-octane (0.25M) and delivered to a warm-walled reactorusing a commercial liquid delivery system. Thermal decomposition todeposit a Pt film was realized using substrate temperature between 200°and 300° C. in the presence of an O₂ /N₂ O mixture. This approachenables fast film growth rates to be realized via increasedmass-transport of reactant to the heated substrate surface and thedeposited Pt film can be used as an electrode for DRAM applications oras a catalytic surface for subsequent reaction (i.e. hydrosilylation,polymerization or hydrogenation, etc.).

EXAMPLE 7

In a modification of examples 4 and 5, a solution of platinum (IV)(cyclopentadienyl) trimethyl was dissolved in a hydrocarbon solvent(0.25M) and delivered to a warm-walled reactor using a commercial liquiddelivery system. Thermal decomposition to deposit a Pt film electrodewas realized using substrate temperature between 500° and 700° C. in thepresence of an O₂ /N₂ O mixture. This approach enables faster filmgrowth rates to be realized via increased mass-transport of reactant tothe heated substrate surface and the deposited Pt film provides superiorperformance as an electrode for DRAM applications. The integrity of theDRAM perovskite capacitor film is preserved in the presence of theoxidizing co-reactants (O₂ /N₂ O mixture) during Pt CVD.

EXAMPLE 8

A solution consisting of platinum (II) bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato) was dissolved in an organicsolvent containing tetrahydrofuran, i-propanol and tetraglyme (8:2:1).The solution was delivered to a warm-walled reactor using a liquiddelivery system and reacted with O₂ /N₂ O mixture to produce aconductive Pt film. In a modification of this method, a co-reactant(i.e., O₃) were used to facilitate the decomposition reaction andformation of pure Pt films. This approach can be used to produceconducting circuits and electrodes for microelectronic applications(i.e., DRAMs).

EXAMPLE 9

A solution consisting of platinum (II) bis(1,1,1,5,5,5-hexafluoro-2-,4-pentanedionato) was dissolved in an organicsolvent containing tetrahydrofuran and tetraglyme (10:1). The solutionwas delivered to a warm-walled reactor using a commercial liquiddelivery system and reacted with H₂ produce a pure platinum film. Theselective deposition of Pt onto metallic surfaces can be realized afterusing a chemical pre-treatment or plasma treatment to modify the surfaceproperties of the substrate. The observed selectivity is enhanced afterpre-treatment of the substrate. In this manner the selective formationof conductive circuits or electrodes may be realized for DRAM or FRAMapplications.

EXAMPLE 10

In a modification of examples 4, 5 and 6, a solution of platinum (IV)(cyclopentadienyl) trimethyl was dissolved at lower concentrations(0.05-0.15M) hydrocarbon solvent (n-octane) and delivered to awarm-walled reactor using a commercial liquid delivery system. Thermaldecomposition to deposit a Pt film electrode was realized usingsubstrate temperature between 500° and 700° C. in the presence of an O₂/N₂ O mixture. This approach enables slower film growth rates to berealized and provides controlled film orientation in thin (≦200 nm)films. The deposited Pt film provides superior performance as anelectrode for DRAM applications. The integrity of the DRAM perovskitecapacitor film is preserved in the presence of the oxidizingco-reactants (O₂ /N₂ O mixture) during Pt CVD.

FIG. 1 is a cross-sectional elevational view of a random access memory(RAM) device 10 comprising a ferroelectric thin film capacitor structure12 with platinum electrodes 14 and 16, formed by chemical vapordeposition of platinum in accordance with the invention.

While the present invention has been illustratively described hereinwith reference to specific aspects, features and embodiments, it will berecognized that the invention is not thus limited, but ratherencompasses within its scope, alternative variations, modifications, andother embodiments, and the invention therefore is intended to be broadlyconstrued to include within its spirit and scope of all such variations,modifications and embodiments.

What is claimed is:
 1. A process for forming a platinum coating on asubstrate in a chemical vapor deposition reactor, comprising the stepsof:(a) providing a platinum source reagent liquid solution,comprising:(i) at least one platinum source compound selected from thegroup consisting of compounds of the formulae:(A) RCpPt(IV)R'₃compounds, of the formula: ##STR9## wherein: R is selected from thegroup consisting of hydrogen, methyl, ethyl, i-propyl, n-propyl,n-butyl, i-butyl, t-butyl, trimethylsilyl and trimethylsilyl methyl; andeach R' is independently selected from the group consisting of methyl,ethyl, i-propyl, n-propyl, n-butyl, i-butyl, t-butyl, trimethylsilyl andtrimethylsilyl methyl; and (B) Pt(β-diketonates)₂ of the formula:##STR10## wherein: each R" is independently selected from the groupconsisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl,t-butyl, trifluoromethyl, perfluoroethyl, and perfluoro-n-propyl, and(ii) a solvent medium therefor; (b) flash vaporizing the platinum sourcereagent liquid solution to form a platinum source reagent vaportherefrom; (c) transporting the platinum source reagent vapor to achemical vapor deposition reactor; and (d) depositing platinum from theplatinum source reagent vapor on the substrate in the chemical vapordeposition reactor, under chemical vapor deposition conditions effectivetherefor.
 2. A process according to claim 1, wherein said chemical vapordeposition conditions comprise the presence of an oxidizing gas.
 3. Aprocess according to claim 2, wherein said oxidizing gas is selectedfrom the group consisting of oxygen (O₂), ozone (O₃), nitrous oxide (N₂O) and mixtures thereof.
 4. A process according to claim 1, wherein saidchemical vapor deposition conditions comprise the absence of a reducinggas.
 5. A process according to claim 1, wherein said chemical vapordeposition conditions comprise the absence of hydrogen gas.
 6. A processaccording to claim 1, wherein the substrate comprises a perovskiteoxide, and said chemical vapor deposition conditions comprise thepresence of an oxidizing gas, and the absence of hydrogen gas.
 7. Aprocess according to claim 1, wherein said chemical vapor depositionconditions comprise the presence of a reducing gas.
 8. A process forforming a platinum coating on a substrate in a chemical vapor depositionreactor, comprising the steps of:(a) providing a platinum source reagentliquid solution, comprising:(i) at least one platinum source compoundselected from the group consisting of compounds of the formulae:(A)RCpPt(IV)R'₃ compounds, of the formula: ##STR11## wherein: R is selectedfrom the group consisting of hydrogen, methyl, ethyl, i-propyl,n-propyl, n-butyl, i-butyl, t-butyl, trimethylsilyl and trimethylsilylmethyl; and each R' is independently selected from the group consistingof methyl, ethyl, i-propyl, n-propyl n-butyl, i-butyl, t-butyl,trimethylsilyl and trimethylsilyl methyl; and (B) Pt(β-diketonates)₂ ofthe formula: ##STR12## wherein: each R" is independently selected fromthe group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl,i-butyl, t-butyl, trifluoromethyl, perfluoroethyl andperfluoro-n-propyl, and (ii) a solvent medium therefor; (b) volatilizingthe platinum source reagent liquid solution to form a platinum sourcereagent vapor therefrom: (c) transporting the platinum source reagentvapor to a chemical vapor deposition reactor; and (d) depositingplatinum from the platinum source reagent vapor on the substrate in thechemical vapor deposition reactor under chemical vapor depositionconditions effective therefor;wherein said chemical vapor depositionconditions comprise the presence of a reducing gas comprising ammonia.9. A process according to claim 1, wherein the substrate comprises adiffusion barrier.
 10. A process according to claim 8, wherein saidplatinum source reagent liquid solution comprises an organoplatinumcompound as said platinum source reagent.
 11. The process of claim 1,wherein the platinum source compound is a compound of the formula:##STR13## wherein: R is selected from the group consisting of hydrogen,methyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl, t-butyl,trimethylsilyl and trimethylsilyl methyl; and each R' is independentlyselected from the group consisting of methyl, ethyl, i-propyl, n-propyl,n-butyl, i-butyl, t-butyl, trimethylsilyl and trimethylsilyl methyl. 12.The process of claim 1, wherein the platinum source compound is acompound of the formula: ##STR14## wherein: each R" is independentlyselected from the group consisting of methyl, ethyl, n-propyl, i-propyl,n-butyl, i-butyl, t-butyl, trifluoromethyl, perfluoroethyl, andperfluoro-n-propyl.
 13. The process of claim 1, wherein the platinumsource compound is selected from the group consisting of:(i) Pt (II) bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato); (ii) Pt (II) bis(2,2,6,6,-tetramethyl-3,5-heptanedionato); (iii) Pt(CO)₂ Cl₂ ; (iv)Pt(PF₃)₄ ; (v) Pt(CH₃)₂ [(CH₃)NC]; (vi) (COD)Pt(CH₃)₂ ; (vii)(COD)Pt(CH₃)(h¹ -C₅ H₅); (viii) (COD)Pt(CH₃)Cl; (ix) (C₅ H₅)Pt(CH₃)(CO);(x) (C₅ H₅)Pt(allyl); (xi) (acac)Pt(CH₃)₃ ; (xii) (C₅ H₅)Pt(CH₃)₃ ; and(xiii) (CH₃ C₅ H₄)Pt(CH₃)₃.wherein acac.=acetylacetonate; C₅ H₅ =h⁵-cyclopentadienyl; CH₃ C₅ H₄ =h⁵ -methylcyclopentadienyl;COD=1,5-cyclooctadiene; and h¹ -C₅ H₅ =h¹ -cyclopentadienyl.
 14. Theprocess of claim 1, wherein the solvent medium comprises a solventselected from the group consisting of: hydrocarbons, alcohols, ethersand esters.
 15. The process of claim 1, wherein the solvent mediumcomprises a solvent selected from the group consisting of: n-butylacetate, tetraglyme, isopropanol, tetrahydrofuran, hexane, heptane,octane, and compatible mixtures of two or more thereof.
 16. A processaccording to claim 7, wherein said reducing gas is hydrogen.
 17. Aprocess according to claim 9, wherein the diffusion barrier comprises amaterial selected from the group consisting of titanium nitride,tantalum nitride, and titanium aluminum nitride.
 18. A process forforming a platinum or platinum-containing film on a substrate by liquiddelivery chemical vapor deposition, comprising providing a liquidsolution of a platinum source reagent, flash vaporizing said liquidsolution to form a platinum source reagent vapor, and contacting theplatinum source reagent vapor with the substrate wherein the chemicalvapor deposition is conducted in the presence of an oxidizing gas andthe absence of hydrogen.
 19. A process for forming platinum metal on asubstrate, comprising depositing platinum by MOCVD on the substrate froma metalorganic platinum precursor, under deposition conditions includingthe presence of a reducing gas comprising ammonia.